19... a3e7 Once again solid and good. The bishop is moving out of the opponent's attack to a better square, protecting the kingside in the process. 20. h2h4 White's play is related to a kingside attack, and this move secures the g5-point for the white pieces. 20... f8d8  21. f1b1  21... a5h5 Swinging over the queen for both defense and counter-actions.